feat(new app-boot): implement an error message to help moving custom …

…app-boot

packages/compat/src/compat-app-builder.ts

@@ -482,10 +482,14 @@ export class CompatAppBuilder {
     writeFileSync(join(this.root, 'package.json'), JSON.stringify(pkg, null, 2), 'utf8');
 
     let resolverConfig = this.resolverConfig(appFiles);
+    let config = this.configTree.readConfig();
+    let contentForConfig = this.contentForTree.readContents();
+
     this.addResolverConfig(resolverConfig);
-    this.addContentForConfig(this.contentForTree.readContents());
-    this.addEmberEnvConfig(this.configTree.readConfig().EmberENV);
+    this.addContentForConfig(contentForConfig);
+    this.addEmberEnvConfig(config.EmberENV);
     this.addAppBoot(this.compatApp.appBoot.readAppBoot());
+    this.outputAppBootError(config.modulePrefix, config.APP, contentForConfig);
     let babelConfig = await this.babelConfig(resolverConfig);
     this.addBabelConfig(babelConfig);
     this.addMacrosConfig(this.compatApp.macrosConfig.babelPluginConfig()[0]);
@@ -601,6 +605,39 @@ export class CompatAppBuilder {
   private addAppBoot(appBoot?: string) {
     writeFileSync(join(locateEmbroiderWorkingDir(this.compatApp.root), 'ember-app-boot.js'), appBoot ?? '');
   }
+
+  // Classic addons providing custom content-for "app-boot" is no longer supported.
+  // The purpose of this error message is to help developers to move the classic addons code.
+  // Developers can deactivate it with useAddonAppBoot build option.
+  private outputAppBootError(modulePrefix: string, appConfig: any, contentForConfig: any) {
+    if (!this.compatApp.options.useAddonAppBoot) {
+      return;
+    }
+
+    // This is the default script provided by
+    // https://github.com/ember-cli/ember-cli/blob/master/lib/utilities/ember-app-utils.js#L103
+    const defaultAppBoot = `
+      if (!runningTests) {
+        require("${modulePrefix}/app")["default"].create(${JSON.stringify(appConfig || {})});
+      }
+    `.replace(/\s/g, '');
+
+    const appBoot = contentForConfig['/index.html']['app-boot'];
+    const diff = appBoot.replace(/\s/g, '').replace(defaultAppBoot, '');
+
+    if (diff.length) {
+      throw new Error(`
+        Your app uses at least one classic addon that provides content-for 'app-boot'. This is no longer supported.
+        With Embroider, you have full control over the app-boot script, so classic addons no longer need to modify it under the hood.
+        The following code is used for your app boot:
+
+        ${appBoot}
+
+        1. If you want to keep the same behavior, copy and paste it to your /app/app-boot.js:
+        2. Once /app/app-boot.js has the content you need, remove the present error by setting "useAddonAppBoot" to false in the build options.
+      `);
+    }
+  }
 }
 
 function defaultAddonPackageRules(): PackageRules[] {

packages/compat/src/options.ts

@@ -102,6 +102,12 @@ export default interface Options extends CoreOptions {
   // 'body-footer', 'test-body-footer'. You need to use this config only to extend
   // this list.
   availableContentForTypes?: string[];
+
+  // Allows you to cancel the warning that at least one classic addon provides
+  // content-for 'app-boot'. This warning brings awareness for developers
+  // switching to Embroider, but is no longer necessary once content-for
+  // 'app-boot' code has been properly moved to the app-side.
+  useAddonAppBoot?: boolean;
 }
 
 const defaults = Object.assign(coreWithDefaults(), {
@@ -114,6 +120,7 @@ const defaults = Object.assign(coreWithDefaults(), {
   packageRules: [],
   allowUnsafeDynamicComponents: false,
   availableContentForTypes: [],
+  useAddonAppBoot: true,
 });
 
 export function optionsWithDefaults(options?: Options): Required<Options> {

tests/fixtures/macro-sample-addon/ember-cli-build.js

@@ -16,6 +16,7 @@ module.exports = function(defaults) {
   */
 
   return maybeEmbroider(app, {
+    useAddonAppBoot: false,
     skipBabel: [
       {
         package: 'qunit',

tests/fixtures/macro-test/ember-cli-build.js

@@ -42,5 +42,7 @@ module.exports = function (defaults) {
   app.import('vendor/prepend/four.js', { prepend: true });
   app.import('vendor/prepend/order.js', { prepend: true });
 
-  return maybeEmbroider(app);
+  return maybeEmbroider(app, {
+    useAddonAppBoot: false,
+  });
 };

tests/scenarios/macro-test.ts

@@ -285,3 +285,39 @@ dummyAppScenarios
       });
     });
   });
+
+dummyAppScenarios
+  .map('macro-sample-addon-useAddonAppBoot', project => {
+    dummyAppScenarioSetup(project);
+    project.mergeFiles({
+      'ember-cli-build.js': `
+        'use strict';
+        const EmberAddon = require('ember-cli/lib/broccoli/ember-addon');
+        const { maybeEmbroider } = require('@embroider/test-setup');
+        module.exports = function(defaults) {
+          let app = new EmberAddon(defaults, {});
+          return maybeEmbroider(app, {
+            useAddonAppBoot: true,
+          });
+        };
+      `,
+    });
+  })
+  .forEachScenario(scenario => {
+    Qmodule(scenario.name, function (hooks) {
+      let addon: PreparedApp;
+
+      hooks.before(async () => {
+        addon = await scenario.prepare();
+      });
+
+      test(`pnpm test`, async function (assert) {
+        let result = await addon.execute('pnpm test');
+        assert.equal(result.exitCode, 1, 'tests exit with errors');
+        assert.true(
+          result.output.includes(`Your app uses at least one classic addon that provides content-for 'app-boot'.`),
+          'the output contains the error message about migrating custom app-boot code'
+        );
+      });
+    });
+  });